Page 22 - Curriculum Visions Dynamic Book

Halogens in plastics
One of the main uses of the halogens (and of chlorine in particular) is in the production of plastics.
One of the simplest procedures is to react products of an oil refinery (such as the gas ethene) with chlorine or fluorine.
Polyvinyl chloride (known as vinyl, polychloroethene or PVC) is made with ethene and chlorine. The reaction that takes place exchanges one chlorine atom for one hydrogen atom of the ethene.
Polyvinyl fluoride (polyfluoroethene or PVF) is made in a similar way using fluorine gas. As with vinyl, a fluorine atom replaces a hydrogen atom. This plastic is heat-resistant.
Using polyvinyl chloride
Polyvinyl chloride is a hard plastic that is rarely used on its own. The material we call vinyl or PVC is actually a mixture of polyvinyl chloride and other compounds that make it soft and flexible.
Although it does not burn, when heated polyvinyl chloride decomposes and releases hydrogen chloride gas, together with carbon monoxide. Both gases are toxic, so this limits the uses for polyvinyl chloride in materials such as furniture fabrics.
The main uses of polyvinyl chloride are in plastic window frames, house cladding, hose pipes, watering cans and waterproof “plastic” sheeting.
Polyvinyl chloride
Polyvinyl chloride is a common thermoplastic, meaning a plastic that can be softened and reworked time after time.
Vinyl chloride is made by reacting ethene or acetylene (gases made from petroleum refining) with hydrochloric acid.
In this reaction, one hydrogen atom in ethene is replaced with a chlorine atom. This change produces a gas whose molecules can be linked together (polymerised) to make polyvinyl chloride.
 Vinyl chloride is often used as house cladding and window frames.
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